/*  mbed Microcontroller Library
    Copyright (c) 2006-2015 ARM Limited

    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
*/
#ifndef MBED_FUNCTIONPOINTER_H
#define MBED_FUNCTIONPOINTER_H

#include <string.h>
#include <stdint.h>

namespace mbed {

    /* If we had variaditic templates, this wouldn't be a problem, but until C++11 is enabled, we are stuck with multiple classes... */

    /** A class for storing and calling a pointer to a static or member function
    */
    template <typename R, typename A1>
    class FunctionPointerArg1 {
      public:
        /** Create a FunctionPointer, attaching a static function

            @param function The static function to attach (default is none)
        */
        FunctionPointerArg1(R(*function)(A1) = 0) {
            attach(function);
        }

        /** Create a FunctionPointer, attaching a member function

            @param object The object pointer to invoke the member function on (i.e. the this pointer)
            @param function The address of the member function to attach
        */
        template<typename T>
        FunctionPointerArg1(T* object, R(T::*member)(A1)) {
            attach(object, member);
        }

        /** Attach a static function

            @param function The static function to attach (default is none)
        */
        void attach(R(*function)(A1)) {
            _p.function = function;
            _membercaller = 0;
        }

        /** Attach a member function

            @param object The object pointer to invoke the member function on (i.e. the this pointer)
            @param function The address of the member function to attach
        */
        template<typename T>
        void attach(T* object, R(T::*member)(A1)) {
            _p.object = static_cast<void*>(object);
            *reinterpret_cast<R(T::**)(A1)>(_member) = member;
            _membercaller = &FunctionPointerArg1::membercaller<T>;
        }

        /** Call the attached static or member function
        */
        R call(A1 a) {
            if (_membercaller == 0 && _p.function) {
                return _p.function(a);
            } else if (_membercaller && _p.object) {
                return _membercaller(_p.object, _member, a);
            }
            return (R)0;
        }

        /** Get registered static function
        */
        R(*get_function(A1))() {
            return _membercaller ? (R(*)(A1))0 : (R(*)(A1))_p.function;
        }

        #ifdef MBED_OPERATORS
        R operator()(A1 a) {
            return call(a);
        }
        operator bool(void) const {
            return (_membercaller != NULL ? _p.object : (void*)_p.function) != NULL;
        }
        #endif
      private:
        template<typename T>
        static R membercaller(void* object, uintptr_t* member, A1 a) {
            T* o = static_cast<T*>(object);
            R(T::** m)(A1) = reinterpret_cast<R(T::**)(A1)>(member);
            return (o->**m)(a);
        }

        union {
            R(*function)(A1);  // static function pointer
            void* object;      // object this pointer
        } _p;
        uintptr_t _member[4]; // aligned raw member function pointer storage - converted back by registered _membercaller
        R(*_membercaller)(void*, uintptr_t*,
                          A1);  // registered membercaller function to convert back and call _m.member on _object
    };

    /** A class for storing and calling a pointer to a static or member function (R ()(void))
    */
    template <typename R>
    class FunctionPointerArg1<R, void> {
      public:
        /** Create a FunctionPointer, attaching a static function

            @param function The static function to attach (default is none)
        */
        FunctionPointerArg1(R(*function)(void) = 0) {
            attach(function);
        }

        /** Create a FunctionPointer, attaching a member function

            @param object The object pointer to invoke the member function on (i.e. the this pointer)
            @param function The address of the void member function to attach
        */
        template<typename T>
        FunctionPointerArg1(T* object, R(T::*member)(void)) {
            attach(object, member);
        }

        /** Attach a static function

            @param function The void static function to attach (default is none)
        */
        void attach(R(*function)(void)) {
            _p.function = function;
            _membercaller = 0;
        }

        /** Attach a member function

            @param object The object pointer to invoke the member function on (i.e. the this pointer)
            @param function The address of the void member function to attach
        */
        template<typename T>
        void attach(T* object, R(T::*member)(void)) {
            _p.object = static_cast<void*>(object);
            *reinterpret_cast<R(T::**)(void)>(_member) = member;
            _membercaller = &FunctionPointerArg1::membercaller<T>;
        }

        /** Call the attached static or member function
        */
        R call() {
            if (_membercaller == 0 && _p.function) {
                return _p.function();
            } else if (_membercaller && _p.object) {
                return _membercaller(_p.object, _member);
            }
            return (R)0;
        }

        /** Get registered static function
        */
        R(*get_function())() {
            return _membercaller ? (R(*)())0 : (R(*)())_p.function;
        }

        #ifdef MBED_OPERATORS
        R operator()(void) {
            return call();
        }
        operator bool(void) const {
            return (_membercaller != NULL ? _p.object : (void*)_p.function) != NULL;
        }
        #endif

      private:
        template<typename T>
        static R membercaller(void* object, uintptr_t* member) {
            T* o = static_cast<T*>(object);
            R(T::** m)(void) = reinterpret_cast<R(T::**)(void)>(member);
            return (o->**m)();
        }

        union {
            R(*function)(void);  // static function pointer
            void* object;        // object this pointer
        } _p;
        uintptr_t _member[4]; // aligned raw member function pointer storage - converted back by registered _membercaller
        R(*_membercaller)(void*, uintptr_t*);  // registered membercaller function to convert back and call _m.member on _object
    };

    typedef FunctionPointerArg1<void, void> FunctionPointer;
    typedef FunctionPointerArg1<void, int> event_callback_t;

} // namespace mbed

#endif
